In conventional movie production etc., to obtain special video effects, a shooting speed of a film camera, that is, the number of frames per second during the shooting varies. For example, if the shooting is made at a speed higher than an ordinary one and played back at the ordinary speed, images are reproduced slowly. Therefore, it is possible to observe easily and in detail a slow motion of, for example, a water droplet falling on a water surface. If the shooting is made at a speed lower than an ordinary one and played back at the ordinary speed, on the other hand, images are reproduced speedily. Therefore, it is possible to present images having high realistic sensations in which a speed sensation is increased in a scene of a fight, car chase, etc.
Further, while in TV program production etc., the digitalization of shooting, editing, broadcasting, etc. for a program has been conventionally involved, film making, etc. is also intended to be digitalized recently owing to improvements in picture quality and decreases in equipment cost as digital technologies has progressed.
Note here that in a case where images are shot using a video camera owing to digitalization of film making etc., to obtain the above-mentioned special video effects, for example, not only image signals obtained by shooting at a predetermined speed but also image signals obtained by shooting at a high speed or a low speed are all recorded in a recording device such as a server so that an image signal of frame images required to obtain the special video effects may be read from these recorded image signals to process the images, thereby creating the image signal that provides special video effects.
In such a manner, the image signals shot at several frame rates are all recorded in the server, so that the server needs to have a large storage capacity. Further, to confirm the special video effects, the image signals must be read from the server to perform image processing, so that those effects cannot be confirmed readily at, for example, a site of film making.
Further, to easily obtain the special video effects such as high speed playback or slow playback, a shooting device that is possible to vary a frame rate during shooting (see, for example, Japanese Patent Application. Laid-open Publication No. 2000-125210) is used to shoot at a frame rate lower than a predetermined one and then, the reproduction thereof is executed at the predetermined frame rate, thereby easily obtaining high speed playback images. Alternatively, by shooting at a higher frame rate and then, the reproduction thereof is executed at the predetermined frame rate, slow playback images can be obtained easily. However, in the case of recording an image signal output from this shooting device, if a recording device has a constant recording frame rate, an image signal having this recording frame rate is generated so that the number of effective picture frames corresponding to the frame rate at the time of shooting may be contained in this image signal. Therefore, if recording the image signal output from the shooting device at the recording frame rate, it is impossible to efficiently record only a signal having a required effective picture frame rate.